Generally, a light-sensitive material comprising an electrically insulated support and photographic component layers is liable to accumulate static electricity thereon due to friction caused by contact with or stripping from the same or foreign materials.
In order to improve the conductivity of a support or photographic component layers, various methods have been proposed. These methods include the addition of various hygroscopic substances, water-soluble inorganic salts, a certain kind of surfactant or a polymer.
However, many of these antistatic agents lose their effects or cause adverse effects on the photographic properties of a light-sensitive material depending on the kind of support or photographic components. Some of them completely lose their antistatic effects after development. In recent years, to obtain an improved antistatic property, there have been developed methods of increasing the conductivity of a light-sensitive material (see Japanese Patent Publication Open to Public Inspection No. 84658/1980). These methods can improve the antistatic property of a light-sensitive material to some extent, but are accompanied by such a problem that emulsion layers tend to separate from a support or easily get scratches when a light-sensitive material is in a wet state (during development). With the recent trend of rapid conveyance or processing of a photofilm, the physical properties of layers have become a matter of crucial importance. Not only in a dry state but also in a wet state, the layers of a light-sensitive material are strongly required to be improved in resistance to peeling-off and scratches.
The applicant previously proposed in Japanese Patent Application Nos. 330860/1988 and 44106/1989 the use of a hardener, an electroconductive polymer and a hydrophobic polymer. The use of these compounds can improve the antistatic property of a light-sensitive material to some extent, but cannot avoid such problems as peeling-off and scratches of layers which may occur during rapid processing.
Diagnosis or examination with an X-ray photograph is usually made by direct observation of a silver image. In such case, the tone of a silver image is very important. Fading or generation of a stain not only hinders smooth observation but also may lead to wrong diagnosis or evaluation. Therefore, a light-sensitive material for X-ray photography is strongly required to form a clear silver image of pure black.
Conventionally, toning agents such as a mercapto compound have been employed to adjust the tone of a silver image.
However, use of such conventional toning agents in the highly-sensitive silver halide light-sensitive material of the present invention results in serious desensitization. Japanese Patent O.P.I. Publication Nos. 285445/1986 and 276539/1987 disclose the use of a specific dye as a toning agent in a silver halide emulsion with a prescribed covering power. These methods are defective in sensitivity and shelf life.
Under such circumstances, the applicant previously proposed in Japanese Patent Application No. 139607/1989 employment of a dispersion of a specific anthraquinone-based dye.
A light-sensitive material containing this dye can produce a silver image of pure black. Further, by changing the kind and amount of the dye, the tone of a silver image can be controlled arbitrarily.
For the antistatic purpose, the inventor tried to provide the preceding electroconductive layer disclosed in Japanese Patent O.P.I. Publication No. 84658/1980 in the anthraquinone dye-containing light-sensitive material. The provision of this layer favorably affected the tone of a silver image, but was unexpectedly accompanied by generation of a large amount of static marks due to insufficient lowering in surface specific resistance.